Highly desirable types of networked multimedia applications should adapt to changes in the environmental conditions in which they operate, such as communication bandwidth, available memory, and battery lifetime, while...
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Highly desirable types of networked multimedia applications should adapt to changes in the environmental conditions in which they operate, such as communication bandwidth, available memory, and battery lifetime, while providing the best possible quality of service (QoS). In this paper we present a software architecture that facilitates the development of adaptive networked multimedia applications which meet this requirement. the proposed software architecture is based on the time-triggered Message-triggered object (TMO) programming scheme and it is implemented as a thin layer on top of the TMO Support Middleware (TMOSM). the new layer, called the QoS Adaptation Support Layer (QASL), includes monitoring and runtime reconfiguration facilities that allow us to easily incorporate QoS-adaptation capabilities into TMO-based multimedia applications. In addition, we introduce a novel, practical approach for establishing the QoS configurations that guide the adaptive behavior of a networked multimedia application. A QoS configuration contains a set of parameters that specify the quality-related characteristics of the media streams which a receiver expects from a sender. We also present a strategy used in QASL for selecting, from a given set of QoS configurations, an optimal configuration by reflecting currently observed environmental conditions. Finally, the effectiveness of the QoS-adaptation mechanisms implemented in QASL is evaluated withthe use of a heterogeneous network based multi-party videoconference application.
the increase of computational power in embedded systems has allowed integrating together hard real-time tasks and rich applications. Complex SW infrastructures containing both RTOS and GPOS are required to handle this...
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the increase of computational power in embedded systems has allowed integrating together hard real-time tasks and rich applications. Complex SW infrastructures containing both RTOS and GPOS are required to handle this complexity. To optimally map system functionality to the hard-RT SW domain, to the general purpose SW domain or to HW peripherals, early performance evaluations at the first steps of the design process are required. Approximate timed co-simulation has been proposed as a fast solution for system modeling at early design steps. this co-simulation technique allows simulating systems at speed close to functional execution, while considering timing effects. As a consequence, system performance estimations can be obtained early, allowing efficient design space exploration and system refinement. To achieve fast simulation speed, the SW code is pre-annotated withtime information. the annotated code is then natively executed, performing what is called native-based co-simulation. Previous native-based simulation environments are not prepared to model multi-OS systems, so the performance evaluation of the different SW domains is not possible. this paper proposes a new embedded system modeling solution considering dual RTOS/GPOS systems. A real Linux-based infrastructure has been modeled an integrated into a state-of-the-art co-simulation environment. the resulting solution is capable of modeling and evaluating all HW and SW system components providing the designer with valuable information for early system optimization and design space exploration.
Modular component-based robot systems require not only an infrastructure for component management, but also scalability as well as real-time properties. Robot Technology (RT)-Middleware is a software platform for such...
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ISBN:
(纸本)9780769535739
Modular component-based robot systems require not only an infrastructure for component management, but also scalability as well as real-time properties. Robot Technology (RT)-Middleware is a software platform for such component-based robot systems. Each component in the RT-Middleware, so-called "RT-component" supporting particular robot functions, is based on Common object Request Broker Architecture (CORBA). Unfortunately, the RT-Middleware lacks the mechanism for real-time control. In this paper, we extend the framework of the RT-components to take care of timing constraints. We first enable tasks to have different periods within each RT-component. We then modify the packet format of the General Inter-ORB Protocol (GIOP) to transfer the information of timing constraints over RT-components. the performance evaluation on ART-Linux shows that the extended RT-component framework improves the schedulability of distributedreal-time tasks, without causing critical overheads in unmarshaling the modified GIOP packets.
Many emerging embedded systems consist of multiple embedded nodes, which are connected through an internal small area network. In such systems, the synchronization between the embedded nodes is essential to provide re...
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ISBN:
(纸本)9780769535739
Many emerging embedded systems consist of multiple embedded nodes, which are connected through an internal small area network. In such systems, the synchronization between the embedded nodes is essential to provide real-time cooperation environment. On small area networks, the severe obstacle for achieving real-time synchronization is the unpredictable overhead of the system software running on the embedded nodes. this is true especially if a traditional operating system has been installed. Despite of these drawbacks, it is quite common to run traditional operating systems on some of the embedded nodes to utilize various existing applications. In this paper, we propose a novel design of communication primitives called RTDiP-Sync for real-timedistributed synchronization over small area networks. Experiment results show that the suggested design can minimize the communication overhead and provide better overhead prediction.
General-purpose middleware, by definition, cannot readily support domain-specific semantics without significant manual efforts in specializing the middleware. this paper presents GRAFT (GeneRative Aspects for Fault To...
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ISBN:
(纸本)9780769535739
General-purpose middleware, by definition, cannot readily support domain-specific semantics without significant manual efforts in specializing the middleware. this paper presents GRAFT (GeneRative Aspects for Fault Tolerance), which is a model-driven, automated, and aspects-based approach for specializing general-purpose middleware with failure handling and recovery semantics imposed by a domain. Model-driven techniques are used to specify the special fault tolerance requirements, which are then transformed into middleware-level code artifacts using generative programming. Since the resulting fault tolerance semantics often crosscut the middleware architecture, GRAFT uses aspect-oriented programming to weave them into the original fabric of the general-purpose middleware. We evaluate the capabilities of GRAFT using a representative case study.
Sensor webs are often composed of servers connected to distributedreal-time embedded (DRE) systems that operate in open environments where operating conditions, workload, resource availability, and connectivity canno...
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ISBN:
(纸本)9780769535739
Sensor webs are often composed of servers connected to distributedreal-time embedded (DRE) systems that operate in open environments where operating conditions, workload, resource availability, and connectivity cannot be accurately characterized a priori. the South East Alaska MOnitoring Network for Science, Telecommunications, Education, and Research (SEAMONSTER) project exhibits many common system management and dynamic operation challenges for effective, autonomous system adaptation in a representative sensor web. these challenges cover both field operation (e.g., power management through system sleep/wake cycles and reaction to local environmental changes) and server operation (e.g., system adaptation for new/modified goals, resource allocation for a changing set of applications, and configuration changes for fluctuating workload). this paper presents the results of integrating and applying quality-of-service (QoS)-enabled component middle-ware, dynamic resource management, and autonomous agent technologies to address these challenges in SEAMONSTER.
We present an architectural framework that provides the foundation for building smart object systems and uses a document centric approach utilizing a profile based artefact framework and a task based application frame...
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ISBN:
(纸本)9780769535739
We present an architectural framework that provides the foundation for building smart object systems and uses a document centric approach utilizing a profile based artefact framework and a task based application framework. Our artefact framework represents an instrumented physical smart objects as a collection of service profiles and expresses these services in generic documents. Applications for smart objects are expressed as a collection of functional tasks (independent of the implementation.) in a corresponding document. A runtimecomponent provides the foundation for mapping these tasks to the corresponding service provider smart objects. there are three primary advantages of our approach- firstly, it allows developers to write applications in a generic way without prior knowledge of the smart objects that could be used by the applications. Secondly;smart object management (locating/accessing/etc.) issues are completely handled by the infrastructure thus application development becomes rapid and simple. Finally;the programming abstraction used in the framework allows extension of functionalities of smart objects and applications very easily. We describe an. implemented prototype of our framework and show examples of its use in a real life scenario to illustrate its feasibility.
Multiprocessor embedded software presents major challenges including the increased complexity and stringent performance requirements raised by parallel processing capability. Although component-based approaches can gr...
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ISBN:
(纸本)9780769535739
Multiprocessor embedded software presents major challenges including the increased complexity and stringent performance requirements raised by parallel processing capability. Although component-based approaches can greatly alleviate the complexity problem, traditional approaches do not provide adequate support for performance requirements on multiprocessors. In this paper, we extend component-based approaches for performance-aware design and analysis of multiprocessor embedded software. the proposed approach begins with a component model that is able to capture concurrent and performance-critical behavior based on UML activity diagrams. It then identifies and exploits potential sources of concurrency within components to produce a multithreaded software design targeted at multiprocessors. We also provide a schedulability analysis that can be used for validating multithreaded software design from a temporal perspective.
AUTOSAR as specified in its current version fosters timing-constraints at application level to support the development of real-time automotive applications. However, the standard's actual specification does not co...
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ISBN:
(纸本)9780769535739
AUTOSAR as specified in its current version fosters timing-constraints at application level to support the development of real-time automotive applications. However, the standard's actual specification does not consider any timing information for its Basic Software. In consequence, the over-all timing-behavior of software running at a specific system node can not be calculated and thus validated at development-time. Even worse, any exchange or modification of Basic Software modules induces unpredictable alteration in system timing, and may even. lead to a severe miss of execution deadlines. Within this paper we solve this issue by using a component based Basic Software architecture, as much as timing-aware software composition for Basic Software components. We therefore introduce timing contracts as enhancement for existing interface contracts, specify a tinting annotation language on a conceptual level, and demonstrate how to capitalize on our approach by calculating timings within composed Basic Software architectures at development time.
A middleware model named ROAFTS (real-timeobject-oriented Adaptive Fault Tolerance Support) has been evolving in the UCI DREAM Lab. over the past decade as the core of a reliable execution engine model for fault-tole...
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ISBN:
(纸本)9780769535739
A middleware model named ROAFTS (real-timeobject-oriented Adaptive Fault Tolerance Support) has been evolving in the UCI DREAM Lab. over the past decade as the core of a reliable execution engine model for fault-tolerant (FT) real-time (RT) distributedcomputing (DC) applications. It is meant to be an integration of various mechanisms for fault detection and recovery in a form that meshes well with high-level RT DC object/component-based programming, in particular, TMO (time-triggered Message-triggered object) programming. Using ROAFTS as a backbone and low-layer middleware, we developed a model and a skeleton implementation for FT DC middleware providing efficient FT execution services for component-based home network applications. Capabilities for management of home information processing devices, including health monitoring of home devices, reconfiguration of device connections, and servicing queries on device status, were added to ROAFTS. those additions were first designed as a network of high-level RT DC components, i.e., TMOs. then the TMO network was extended into an FT TMO network by applying the replication scheme called the PSTR (Primary-Shadow TMO Replication) scheme and incorporating a component responsible for reconfiguring TMO replicas. this extension of ROAFTS is called ROAFTS-HNE (Home Network Extension) and its architecture is presented here. In addition, during the development of the ROAFTS-HNE model, we formulated a new approach for applying the PSTR scheme to RT DC components supported by ROAFTS. Finally, evaluations of the recovery times of a prototype implementation have been conducted.
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